Synthesizing specifications for real time applications that involve distributed communication protocol entities from a service specification, which is modeled in the UML state machine with composite states, is a time-consuming and labor-intensive task. Existing synthesis techniques for UML-based service specifications do not account for timing constrains and, therefore, cannot be used in real time applications for which the timing constraints are crucial and must be considered. In this paper, we address the problem of time assignment to the events defined in the service specification modeled in UML state machine. In addition, we show how to extend a technique that automatically synthesizes UML-based protocol specifications from a service specification to consider the timing constraints given in the service specification. The resulting synthesized protocol is guaranteed to conform to the timing constraints given in the service specification.